igneous
Rounded gray pebble, likely granite or granitic gneiss
Probable quartz–feldspar–mica aggregate; exact identification is limited by the blurred image
AI-generated identification · may be incorrectGray, mottled, fine-to-medium granular texture with dull to weakly vitreous luster; likely Mohs hardness 6–7, with no obvious cleavage on the rounded surface. Specific gravity is approximately 2.6–2.7.
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Physical properties
Gray, mottled, fine-to-medium granular texture with dull to weakly vitreous luster; likely Mohs hardness 6–7, with no obvious cleavage on the rounded surface. Specific gravity is approximately 2.6–2.7.
Formation & geological history
Likely weathered from crystalline continental bedrock and rounded by stream or shoreline transport; the original rock may be Precambrian to younger, depending on locality.
Uses & applications
Common granite is used as aggregate, building stone, paving, and monuments; an ordinary pebble generally has negligible commercial value.
Geological facts
The light grains are probably quartz or feldspar, while darker grains may be biotite, hornblende, or other mafic minerals.
Field identification & locations
Look for interlocking visible grains and a speckled gray appearance; a streak test, hardness test, and fresh break would help distinguish granite from basalt, gneiss, or concrete. Common worldwide in streambeds, glacial deposits, and rocky shorelines.
